The invention relates to conjugated polymers and copolymers containing triptycene moieties.
There is a considerable industrial demand for large-area solid-state light sources for a number of applications, predominantly in the area of display elements, display-screen technology and illumination technology. The requirements made of these light sources cannot at present be met in an entirely satisfactory manner by any of the existing technologies.
As an alternative to conventional display and illumination elements, such as incandescent lamps, gas-discharge lamps and non-self-illuminating liquid-crystal display elements, electroluminescent (EL) materials and devices, such as light-emitting diodes (LEDs), have already been in use for some time.
Besides inorganic electroluminescent materials and devices, low-molecular-weight organic electroluminescent materials and devices have also been known for about 20 years (see, for example, U.S. Pat. No. 3,172,862). Until recently, however, such devices were greatly restricted in their practical usability.
WO 90/13148 and EP-A-0 443 861 describe electroluminescent devices which contain a film of a conjugate polymer as light-emitting layer (semiconductor layer). Such devices offer numerous advantages, such as the possibility of producing large-area, flexible displays simply and inexpensively. In contrast to liquid-crystal displays, electroluminescent displays are self-illuminating and therefore do not require any additional back-lighting source.
A typical device in accordance with WO 90/13148 consists of a light-emitting layer in the form of thin, dense polymer film (semiconductor layer) which comprises at least one conjugated polymer. A first contact layer is in contact with a first surface, a second contact layer is in contact with a further surface of the semiconductor layer. The polymer film of the semiconductor layer has a sufficiently low concentration of extrinsic charge carriers so that, on application of an electric field between the two contact layers, charge carriers are introduced into the semiconductor layer, the first contact layer being positive relative to the other, and the semiconductor layer emitting radiation. The polymers used in such devices are conjugated. The term conjugated polymer is taken to mean a polymer which has a delocalized electron system along the main chain. The delocalized electron system provides the polymer with semiconductor properties and enables it to transport positive and/or negative charge carriers with high mobility.
The polymeric material for the light-emitting layer using WO 90/13148 is poly(p-phenylenevinylene), and it is proposed to replace the phenyl group in a material of this type by a heterocyclic or a fused carbocyclic ring system. In addition, poly(p-phenylene), PPP, is also used as electroluminescent material (G. Grem et al., Synth. Met. 1992, 51, page 383).
Although good results have been achieved with these materials, the color purity, for example, is still unsatisfactory. Furthermore, it is virtually impossible to generate blue or white emission with the polymers disclosed hitherto.
Since, in addition, the development of electroluminescent materials, in particular based on polymers, can in no way be regarded as complete, the producers of illumination and display devices are interested in an extremely wide variety of electroluminescent materials for such devices.
One of the reasons for this is that only the interaction of the electroluminescent materials with the other components of the devices allows conclusions to be drawn on the quality of the electroluminescent material too.
German Patent Application 197 44 792.9, which has an earlier priority date and was published before the priority date of the present application, describes the use of triptycene derivatives as electroluminescent materials. This application relates to the monomeric triptycene derivatives, which, in order to be used as electroluminescent materials, are applied in the form of a film to a substrate by known methods, such as dipping, spin coating, vapor deposition or buffering out under reduced pressure.
The object of the present invention is to provide novel polymeric electroluminescent materials containing triptycene moieties which are suitable, on use in illumination or display devices, for improving the property profile of these devices.
The object has been achieved by a conjugated polymer containing
a) from 1 to 100 mol % of at least one recurring unit RU1 of the general formula (I)
xe2x80x94Bxe2x80x94Trxe2x80x94Axe2x80x94xe2x80x83xe2x80x83(I)
xe2x80x83in which Tr is a triptycenylene radical of the general formula (II) 
or of the general formula (III) 
or of the general formula (IV) 
where R1 to R16=H, linear or branched C1-C22-alkyl or alkoxy, in which one or more non-adjacent CH2 groups may be replaced by xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94, xe2x80x94COxe2x80x94, xe2x80x94COOxe2x80x94, xe2x80x94Oxe2x80x94COxe2x80x94, an amino or amide group and in which one or more H atoms may be replaced by F atoms, or C6-C20-aryl or aryloxy, COOR, SO3R, CN, halogen or NO2,
where G, L and where appropriate G1 and L1=CR17, N, P, As, where R17=H, C1-C22-alkyl or alkoxy, where one or more non-adjacent CH2 groups may be replaced by xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94, xe2x80x94COxe2x80x94, xe2x80x94COOxe2x80x94, xe2x80x94Oxe2x80x94COxe2x80x94, an amino or amide group and in which one or more H atoms may be replaced by F atoms, or C6-C20-aryl, halogen or CN,
A and B are a single bond, a vinylene radical which is optionally substituted by H, linear or branched C1-C22-alkyl or alkoxy, in which one or more non-adjacent CH2 groups may be replaced by xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94, xe2x80x94COxe2x80x94, xe2x80x94COOxe2x80x94, xe2x80x94Oxe2x80x94COxe2x80x94, an amino or amide group and in which one or more H atoms may be replaced by F atoms, or C6-C20-aryl or aryloxy, C3-C20-heteroaryl, COOR, SO3R, CN, halogen, NO2, amino, alkylamino or dialkylamino, or are an ethynylene radical, an arylene radical of the general formula (V) 
where R18 to R21 are as defined above for R1 to R16,
a heteroarylene radical of the general formula (VI) 
where X and Y=N or CR22, and Z=O, S, NR23, CR24R25, CR26=CR27 or CR28=Nxe2x80x94, in which R22 to R28 are as defined above for R1 to R16, or a spirobifluorenylene radical of the general formula (VII) 
where R29 to R32 are as defined above for R1 to R16, and
b) from 0 to 99 mol % of at least one recurring unit RU2 of the general formula (VIII) 
where R33 to R36 are as defined above for R1 to R16, or of the general formula (IX) 
where X, Y and Z are as defined above, and D is a single bond, a vinylene radical which is optionally substituted by H, linear or branched C1-C22-alkyl or alkoxy, in which one or more non-adjacent CH2 groups may be replaced by xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94, xe2x80x94COxe2x80x94, xe2x80x94COOxe2x80x94, xe2x80x94Oxe2x80x94COxe2x80x94, an amino or amide group and in which one or more H atoms may be replaced by F atoms, or C6-C20-aryl or aryloxy, C3-C20-heteroaryl, COOR, SO3R, CN, halogen, NO2, amino, alkylamino or dialkylamino, or is an ethynylene radical.
In a preferred embodiment of the invention, L, G and where appropriate L1 and G1 are a CH group.
A and B are a single bond, an optionally substituted vinylene radical, an ethynylene radical, an optionally substituted arylene radical, an optionally substituted heteroarylene radical or a spirobifluorenylene radical.
Preferred substituted vinylene radicals are methylvinylene, phenylvinylene and cyanovinylene.
Particular preference is given to an unsubstituted vinylene radical.
Preferred arylene radicals are 1,4-phenylene, 2,5-tolylene, 1,4-naphthylene, 1,9 antracylene, 2,7-phenantrylene and 2,7-dihydrophenantrylene.
Preferred heteroarylene radicals are 2,5-pyrazinylene, 3,6-pyridazinylene, 2,5-pyridinylene, 2,5-pyrimidinylene, 1,3,4-thiadiazol-2,5-ylene, 1,3-thiazol-2,4-ylene, 1,3-thiazol-2,5-ylene, 2,4-thiophenylene, 2,5-thiophenylene, 1,3-oxazol-2,4-ylene, 1,3-oxazol-2,5-ylene and 1,3,4-oxadiazol-2,5-ylene, 2,5-indenylene and 2,6-indenylene.
Methods for the synthesis of these monomers are based, for example, on the synthesis of 9,9xe2x80x2-spirobifluorene, for example from 2-bromobiphenyl and fluorenone via a Grignard synthesis, as described by R. G. Clarkson, M. Gomberg, J. Am. Chem. Soc. 1930, 52, page 2881, which is subsequently further substituted in a suitable manner.
Functionalizations of 9,9xe2x80x2-spirobifluorene are described, for example, in J. H. Weisburger, E. K. Weisburger, F. E. Ray, J. Am. Chem. Soc. 1959, 72, 4253; F. K. Sutcliffe, H. M. Shahidi, D. Paterson, J. Soc. Dyers Colour 1978, 94, 306; and G. Haas, V. Prelog, Helv. Chim. Acta 1969, 52, 1202.
The desired substitution pattern of the 9,9xe2x80x2-spirobifluorene monomer is obtained significantly more favorably if the spiro linkage is carried out starting from suitably substituted starting materials, for example with 2,7-difunctionalized fluorenones, and the 2xe2x80x2,7xe2x80x2-positions which are still free are then, if desired, further functionalized after build-up of the spiro atom (for example by halogenation or acylation, with subsequent Cxe2x80x94C linkage after conversion of the acetyl groups into aldehyde groups, or by build-up of heterocycles after conversion of the acetyl groups into carboxylic acid groups).
The further functionalization can be carried out by methods known from the literature, as described in standard works on organic synthesis, for example Houben-Weyl, Methoden der Organischen Chemie [Methods of Organic Chemistry], Georg-Thieme Verlag, Stuttgart, and in the corresponding volumes of the series xe2x80x9cThe Chemistry of Heterocyclic Compoundsxe2x80x9d by A. Weissberger and E. C. Taylor (editors).
The substituted triptycene or heterotriptycene basic structures are accessible by various synthetic routes. At this point, mention may be made by way of example, but not in a restrictive manner, of the following:
1. Syntheses from substituted anthracene (or substituted acridine or substituted phenazine) and decahydroaromatic compounds, for example starting from
a) substituted o-fluorobromofluorobenzenes with reactive metals, such as, for example, magnesium, for example analogously to G. Wittig, Org. Synth. IV 1963, 964;
b) substituted o-dihalobenzenes and butyllithium with elimination of metal halide, for example analogously to H. Hart, S. Shamouilian, Y. Takehira J. Org. Chem. 46 (1981) 4427;
c) substituted monohalobenzenes and strong bases with elimination of hydrogen halide, for example analogously to P. G. Sammes, D. J. Dodsworth, J. C. S. Chem. Commun. 1979, 33.
d) substituted anthranilic acid derivatives and isoamyl nitrile, for example analogously to C. W. Jefford, R. McCreadie, P. Mxc3xcller, B. Siegfried, J. Chem. Educ. 48 (1971) 708.
e) a review of the preparation of a series of substituted dehydroaromatc compounds is given in Houben-Weyl, Methoden der Organischen Chemie [Methods of OrganicChemistry], 4th Edition 1981, Volume V/2b, pp.615, Georg-Thieme-Veriag, Stuttgart.
2. Syntheses by deamination of substituted anthracene-9,10-imines, for example analogously to L. J. Kricka, J. M. Vemon, J. C. S. Perkin I, 1973, 766.
3. Synthesis by cycloaddition of substituted 1,4-quinones with substituted anthracene derivatives, for example analogously to E. Clar, Chem. Ber. 64 (1931) 1676; W. Theilacker, U. Berger-Brose, K. H. Beyer, Chem. Ber. 93 (1960) 1658; P. D. Bartlett, M. J. Ryan, J. Am. Chem. Soc. 64 (1942) 2649; P. Yates, P. Eaton, J. Am. Chem. Soc. 82 (1960) 4436. V. R. Skvarchenko, V. K. Shalaev, E. I. Klabunovskii, Russ. Chem. Rev. 43 (1974) 951;
Further syntheses of substituted triptycenes are given by way of example in C. F. Wilcox, F. D. Roberts, J. Org. Chem. 30 (1965) 1959; T. H. Regan, J. B. Miller, J. Org. Chem. 32 (1967) 2798.
Further syntheses for heterotrypticenes are given, for example, in D. Hellwinkel et al., Chem. Ber. 111 (1978); or D. Hellwinkel et al., Angew. Chem. 24 (1969) 1049; N. P. McCleland et al., J. Am. Chem. Soc. (1927) 2753; N.A.A. Al-Jabar et al., J. Organomet. Chem. 287 (1985) 57.
Bistriptycene basic structures or heterobistriptycene basic structures are likewise accessible by various synthetic routes. Mention may be made at this point by way of example of the following:
1) Syntheses from substituted anthracene (or substituted acridine or substituted phenazine) and substituted didehydrobenzenes, for example analogously to H. Hart, S. Shamouilian, Y. Takehira J. Org. Chem. 46 (1981) 4427;
2) Synthesis by cycloaddition of substituted anthracene derivatives with 1,4-benzoquinone, for example analogously to E. Clar, Chem. Ber. 64 (1931) 1676; P. Yates, P. Eaton, J. Am. Chem. Soc. 82 (1960) 4436; W. Theilacker, U. Berger-Broske, K. H. Beyer, Chem. Ber. 93 (1960) 1658.
Further syntheses are given by way of example in H. Hart et al., Tetrahedron 42 (1986) 1641; V. R. Skvarchenko et al., Russ. Chem. Rev. 43 (1974) 951; V. R. Skvarchenko et al., J. Org. Chem. USSR (Engl. trans.) 3 (1967) 1477.
In a preferred embodiment, the polymers according to the invention consist of precisely one type of recurring units RU1 (homopolymers). Particular preference is given to homopolymers in which A is selected from the group consisting of 2,5-thiophenylene, 2,5-oxadiazolylene, 1,4-phenylene, vinylene and ethynylene, and B is a single bond.
Preferred homopolymers are furthermore those in which A and B are identical and are selected from the group consisting of 2,5-thiophenylene, 1,4-phenylene, vinylene and ethynylene.
In a further preferred embodiment, the polymers according to the invention comprise from 1 to 99 mol % of recurring units RU2 (copolymers). The copolymers preferably comprise from 5 to 95 mol % of recurring units RU2, particularly preferably from 10 to 90 mol % of recurring units RU2.
Preferred copolymers are furthermore those in which A is a single bond and B is a single bond, a vinylene group or ethynylene group. Particular preference is given to copolymers in which B is a vinylene group.
Preferred copolymers are furthermore binary copolymers comprising recurring units RU1 and recurring units RU2 of the general formula (VIII) or (IX).
Preferred copolymers are furthermore quatemary copolymers comprising recurring units RU1 and two types of recurring units RU2 of the general formula (VIII) or (IX).
Particularly preferred copolymers are those in which the recurring units RU2 are recurring units of the general formula (VIII).
Particular preference is furthermore given to copolymers in which the group D in the general formulae (VIII) and (IX) is a vinylene group.
The polymers are prepared by conventional methods of polymerization reaction, as described, for example, in xe2x80x9cMakromolekxc3xclexe2x80x9d [Macromolecules] by Hans-Georg Elias (Hxc3xcthig and Wepf Verlag Basle-Heidelberg-New York) or in Houben-Weyl, Methoden der organischen Chemie [Methods of Organic Chemistry], Vol. XIV, Makromolekulare Stoffe [Macromolecular Substances] (G. Thieme, Stuttgart, 1961 and 1963). The selection is in each case made depending on the type of functionalization of the monomers and the desired molecular weight.
Starting from the monomers obtained as described, the polymerization to give polymers according to the invention is possible by a plurality of processes.
For example, halogen derivatives of the triptycenes can be polymerized oxidatively (for example using FeCl3, see, inter alia, P. Kovacic et al., Chem. Ber., 87, 1987, 357 to 379; M. Wenda et al., Macromolecules 25, 1992, 5125) or electrochemically (see, inter alia, N. Saito et al., Polym. Bul. 30, 1993, 285).
Polymers according to the invention can likewise be prepared from dihalogen derivatives by polymerization with copper/triphenylphosphine catalysis (see, for example, G. W. Ebert et al., J. Org. Chem. 1988, 53, 4829, or nickel/triphenylphosphine catalysis (see, for example, H. Matsumoto et al., J. Org. Chem. 1983, 48, 840).
Aromatic diboronic acids and aromatic dihalides or aromatic haloboronic acids can be polymerized with palladium catalysis (Suzuki coupling) (see, for example, M. Miyaura et al., Synth. Commun. 11, 1981, 513; R. B. Miller et al., Organometallics 3, 1984, 1261). In a similar manner, aromatic distannanes and aromatic dihalides can be polymerized (see, for example, J. K. Stille, Angew. Chem. Int. Ed. 25,1986, 508).
Furthermore, dibromoaromatic compounds can be converted into dilithio or di-Grignard compounds. These can then be polymerized with further dihaloaromatic compounds by means of CuCl2 (see, for example, G. Wittig et al., Liebigs Ann. Chem. 704, 91,1967; H. A. Stabb et al., Chem. Ber. 100, 1967, 293 and T. Kaufmann, Angew. Chem. 86,1974, 321).
Particular methods are necessary for the preparation of poly(triptycenyl-vinylenes), which are likewise according to the invention. Thus, the synthesis can be carried out, for example, by polycondensation of para-dihalomethyl-substituted triptycene derivatives. The polymerization here is carried out in a suitable solvent by addition of base (see, for example, H.Hxc3x6rhold et al., Makromol. Chem, Macromol. Symp. 12, 1987, 229-258). Precursor polymerization is likewise possible; in this case, a poly(triptycenylene-vinylene) is prepared by elimination of a precursor radical present (for example CH2S+R2) by heat treatment or base treatment (see, for example, R. A. Wessling, J. Polym. Sci; Polym. Sym. 72, 1985, 55-66).
Further ways of preparing poly(triptycenylenes) are, for example, Homer polymerization and Wittig polymerization. In these, two types of monomer (aldehydes with phosphonates (Homer polymerization); aldehydes with triarylalkylphosphonium salts (Wittig polymerization)) are polymerized with addition of a base. In general, these preparation processes are described, for example, in DD 84272, H. Hxc3x6rhold et al., Makromol. Chem, Macromol. Symp. 12, 1987, 229-258 and H. Horhold et al., Z. Chem. 27, 1987, 126.
Cyano-substituted poly(triptycenylvinylenes) can be prepared by the Knoevenagel reaction. In this, a bis-cyanomethyl-substituted aromatic compound is reacted with a dialdehyde with addition of a base (see, for example, H. Hxc3x6rhold et al., Plaste und Kautschuk 17, 1970, 84).
For the preparation of copolymers, triptycene or heterotriptycene monomers can be polymerized together with one or more comonomers, as described, for example, in xe2x80x9cMakromolekuilexe2x80x9d [Macromolecules] by Hans-Georg Elias (Hxc3xcthig and Wepf Verlag Basle-Heidelberg-New York), pp. 32-40.
The polymers according to the invention can be worked up by known methods which are familiar to the person skilled in the art, as described, for example, in D. Braun, H. Cherdron, W. Kem, Praktikum der makromolekularen organischen Chemie [Practical Macromolecular Organic Chemistry], 3rd Edn. Hxc3xcthig Verlag, Heidelberg, 1979, pp. 87-89 or R. J. Young, P. A. Lovell, Introduction to Polymers, Chapman and Hall, London 1991. For example, the reaction mixture can be filtered, diluted with aqueous acid, extracted and the crude product obtained after drying and stripping-off of the solvent can be further purified by reprecipitation from suitable solvents with addition of precipitants. Polymer-analogous reactions can subsequently be carried out for further functionalization of the polymer. Thus, for example, terminal halogen atoms can be removed reductively by reduction with, for example, LiAlH4 (see, for example, J. March, Advanced Organic Chemistry, 3rd Edn. McGraw-Hill, p. 510).
The polymers according to the invention are suitable for use as electroluminescent materials.
For the purposes of the present invention, the term xe2x80x9celectroluminescent materialsxe2x80x9d is taken to mean materials which can be used as or in an active layer in an electroluminescent device. The term xe2x80x9cactive layerxe2x80x9d means that the layer is capable of emitting light (light-emitting layer) on application of an electric field and/or that it improves the injection and/or transport of the positive and/or negative charges (charge injection or charge transport layer). In addition, the use as electron-blocking layer or hole-blocking layer is a use according to the invention.
The invention therefore also relates to the use of the polymers according to the invention as electroluminescent material. The invention furthermore relates to an electroluminescent material which comprises the polymers according to the invention.
In order to be used as electroluminescent materials, the polymers according to the invention are generally applied in the form of a film to a substrate by known methods familiar to the person skilled in the art, such as dipping, spin coating, vapor deposition or buffering-out under reduced pressure.
The invention likewise relates to an electroluminescent device having one or more active layers, where at least one of these active layers comprises one or more polymers according to the invention. The active layer can be, for example, a light-emitting layer and/or a charge-transport layer and/or a charge-injection layer. The general construction of electroluminescent devices of this type is described, for example, in U.S. Pat. No. 4,539,507 and U.S. Pat. No. 5,151,629.
They usually contain an electroluminescent layer between a negative electrode and a positive electrode, where at least one of the electrodes is transparent for part of the visible spectrum. In addition, one or more electron-injection and/or electron-transport layers can be introduced between the electroluminescent layer and the negative electrode and/or one or more hole-injection and/or hole-transport layers can be introduced between the electroluminescent layer and the positive electrode. Suitable negative electrodes are preferably metals or metal alloys, for example Ca, Mg, Al, In or Mg/Ag. The positive electrodes can be metals, for example Au, or other metallically conducting substances, such as oxides, for example ITO (indium oxide/tin oxide) on a transparent substrate, for example made of glass or a transparent polymer.
In operation, the negative electrode is set to a negative potential compared with the positive electrode. Electrons are injected by the negative electrode into the electron-injection layer/electron-transport layer or directly into the light-emitting layer. At the same time, holes are injected by the positive electrode into the hole-injection layer/hole-transport layer or directly into the light-emitting layer.
The injected charge carriers move through the active layers toward one another under the effect of the applied voltage. This results in electron/hole pairs recombining at the interface between the charge-transport layer and the light-emitting layer or within the light-emitting layer with emission of light. The color of the emitted light can be varied by means of the materials used as light-emitting layer.
Electroluminescent devices are used, for example, as self-illuminating display elements, such as control lamps, alphanumeric displays, signs and in opto-electronic couplers.
Compounds of the formula (I) are furthermore suitable, for example, for use in optical storage media, as photorefractive materials, for nonlinear-optical (NLO) applications, as optical brighteners and radiation converters and, preferably, as hole-transport materials in photovoltaic cells, as described, for example, in WO-A 97/10 617 and DE-A 197 11 713, to which reference is made for these applications.
The polymers according to the invention have excellent solubility in organic solvents. The film-forming properties are excellent compared with poly(p-phenylene). Particular emphasis should be placed on the temperature stability of the emission color, i.e. the fact that the morphology of the polymer is not destroyed with thermal activation. Furthermore, high charge carrier mobilities are observed.